1997 F150 XLT 4.6 with 100K miles. Check engine light came back on after I had a previous code cleared up. Previous code was #4 misfire. Turned out that the #4 plug, which was supposed to be new had not in fact been replaced and was fouled closed. New plug installed, plug wires were misplaced out of order. Wires properly installed. Had the injectors cleaned as recommended by shop. Ran fine, proper idle rpm and engine response. Within 5 miles light came back on. Took it back to shop, figured the light back on was related to work done. I was informed that the bank one was lean and I needed a new fuel pump. I had them check for good plug wire contact and the PCV boots condition. They insist that the fuel pump is not holding pressure. If so, why not both banks running lean? Any ideas on what the problem could be. Would there be anything related to having the injectors cleaned causing this lean condition in bank one?

 

Am thinking like you, why only one bank lean? Don't like the ideal of pump leaking causing pressure drop but maybe with these newer check valves to prevent cross feeding it possible. Need other input on that subject.

Another question on the pressure leaking off, how does this engine start in the AM?

Back to the lean bank, am getting totally confused on this code and its causes, will elaborated more on this as I find out, for now possibly just a hick-up in the system.

 

Yo Bill,
She cranks and runs just like the day I test drove her at the dealer. February 1996. That is why I refused to let them throw parts at the problem. It seems to be many things that can cause this code. Again, only in one bank and bank one being the side where the plug was replaced and wires were crossed.

Thanks, and I'll appreciated anything you come up with.

 

I have a 98 4.6 with the exact same problem, butit happens about every couple of weeks. Mine is in great shape other than that and 160,000 miles

 

I have the 4.2L, prior to the completeing the TSB, I would get this code in addition to the occasional P0174. Been good for a 1 1/2 years. The other day was advising another member about idle speed without the IAC connected (setting base idle) expected to receive an IAC code and the P0174 came up, I mean WTF. Erased it and waiting.

 

Well, I picked up the Ole Girl from the "shop" and the engine light was gone. After 20 or so miles the Check Engine light is back on. They must have cleared the codes. It starts and runs GREAT. No wierd rpm issues. Power is right on tap. I am going to pull the codes again. The last thing the service manager at the "shop" said was it is still going to need a fuel pump. $517.00 (279 for parts) I can get one with Lifetime warranty for 110. Does the tank need to be removed to do this replacement? I am not sure it even needs a fuel pump???

 

All shops drop the tank to change the pump, some member here would rather tilt up the bed to do the work. Does the pump make strange noises, wondering why the diognosis of the pump is going bad?

 

Are you sure the shop did a pressure test on the fuel system? You can easily verify this yourself with a simple fuel pressure gauge from any auto parts store. Connect gauge to valve on the fuel rail, crank engine - pressure should stay around 30-40psi. Turn key off, verify pressure stays above 30psi for 5-10min.

 

I have the same code on my truck 1997 Code came on with about 175 -180 thousand on it. Changed the O2 sensor checked the fuel pressure fule filter air filter. I havnt done and extensive vacum leak check. New plugs and wires. Ran injector cleaner through it. It stays of long enough to get it inspected and has over 210 thousand on it now so I just leave it. I cleared it once after I ran a bottle of sea foam through and it stayed off for about 10,000 miles.

 

I have a 4.2 v6 and mine said I had that bank problem turned out I had a vacuum leak an tht was causin it